Freddy Guevara (3R), first vice president of the National Assembly makes declarations to the media at the National Assembly in Caracas, August 19, 2017. REUTERS/Andres Martinez Casares

Venezuela's opposition-controlled congress on Saturday rejected the self-proclaimed law-making authority of a new legislative superbody elected last month at the behest of President Nicolas Maduro.

Congress's declaration of resistance followed statements from a group of 12 regional nations plus the United States on Friday, saying they would continue to regard congress, not the new constituent assembly, as the Venezuela's only legitimate lawmaking body.

"This is a congress in resistance of an armed military dictatorship that took over its authority and gained militarily what it could not gain at the ballot box," congress Vice President Freddy Guevara said in a special session.

The opposition won control of congress in 2015. But Maduro's loyalist Supreme Court has tossed out every law it has passed as the oil-rich country slips deeper into a recession exacerbated by triple-digit inflation and acute shortages of food and medicines.

The constituent assembly was elected in late July to re-write the constitution, which the unpopular Maduro billed as the only solution to bring about peace after more than four months of deadly opposition protests. The opposition boycotted the election, calling it an affront to democracy.

On Friday the 545-member assembly granted itself authority to pass laws on its own.

A bloc of countries calling itself the Lima Group, including Peru, Argentina, Brazil, Canada, Colombia and seven other nations in the hemisphere late on Friday joined the United States in criticizing the assembly for "usurping" the powers of congress.

The assembly has blamed the opposition for the unrest that killed more than 125 people in recent months as security forces met rock-throwing protesters with rubber bullets and water cannon. The United Nations says government troops used excessive force in many cases.

The assembly's new truth commission will investigate opposition candidates running in October gubernatorial elections, to see if they were involved in the deadly protests. Considering that many opposition figures supported the demonstrations, the commission could hobble their efforts at winning governorships in the upcoming vote.

Anti-government marches have stalled since the assembly was inaugurated on Aug. 5, and the opposition was stunned by a threat of U.S. military action in Venezuela issued by President Donald Trump on Aug. 11.

The threat played into Maduro's hands by supporting his oft-repeated assertion that the U.S. "empire" wants to invade Venezuela to steal its oil. It was an idea that had been easily dismissed as absurd by opposition and U.S. officials before Trump's surprise statement that "a military option" was on the table for dealing with Venezuela's political and social crisis.